Using GeometryReader without modifying the view

I am trying to use GeometryReader here to build views based on the size available, however because this view is embedded in a parent view with padding, it is not drawing correctly. I know from other SO answers, some have said to use the GeometryReader as an .overlay or .background but I can’t figure out a way to do that here:

 var body: some View {
        GeometryReader { geometry in
            HStack(alignment: .bottom, spacing: 5) {
                ForEach(dataStore.sleepOrAwakeSpans) { sleepOrAwakeSpan in
                    VStack {
                        RoundedRectangle(cornerRadius: 5.0)
                            .frame(width: geometry.size.width * CGFloat((sleepOrAwakeSpan.endTime.timeIntervalSince(sleepOrAwakeSpan.startTime) / athlyticDataStore.sleepOrAwakeSpans.map { $0.endTime.timeIntervalSince($0.startTime) }.reduce(0, +))), height: 25)
                            .foregroundColor(sleepOrAwakeSpan.asleep == false ? TrackerConstants.scaleLevel6Color : TrackerConstants.scaleLevel2Color)
                    }
                }
            }
        }
    }